The present invention generally relates to a vapor vent valve used in combination with a fuel tank employed in an automotive vehicle and, more particularly, to a vapor vent valve capable of being integrally molded directly into a polymeric fuel tank employed in an automotive vehicle.
Fuel tanks employed in automotive vehicles require means for keeping the internal pressure within the fuel tanks substantially in equilibrium with atmosphere. Various conditions, such as extremes of heat and cold, will affect the internal pressure within the internal chamber of a fuel tank. Likewise, as fuel is withdrawn from a tank, the internal pressure therein will also change. Vent/relief mechanisms have been employed in the prior art in order to keep the internal pressure within a tank substantially at equilibrium with atmosphere. Such a vent/valve mechanism may comprise a vapor vent valve connected, by way of a conduit, to a carbon canister where vapors from the tank are collected and eventually delivered to the engine for combustion.
The vapor vent valves employed in the vent/relief mechanisms normally include means for preventing fuel from leaking out of a tank if, for example, the vehicle travels along a steep incline causing fuel to enter into the vapor vent valve or if a roll-over accident occurs. The means employed for preventing fuel leakage may comprise a known internal shut-off mechanism included within the vapor vent valve.
It is also known in the prior art to use fuel tanks made from polymeric materials, such as polyethylene, in automotive vehicles. Such fuel tanks are advantageous because they resist corrosion and can be easily formed having various shapes and sizes, thus permitting flexibility in their design. Further, since polymeric fuel tanks are lightweight, they make the vehicles in which they are employed more fuel efficient and economical to operate.
Arrangements for mounting vapor vent valves onto fuel tanks are known in the prior art. One such arrangement is disclosed in U.S. Pat. No. 4,753,262, wherein an outer plastic casing of the valve is formed with external threads for threadably connecting the valve within an opening in a fuel tank.
Another arrangement for attaching the vapor vent valve to a fuel tank is taught in copending application Ser. No. 07/572,078 (CIP), which teaches the hot plate welding of the vapor vent valve directly to the outer surface of the fuel tank wall. This process requires the drilling of an opening in the molded fuel tank and welding the vapor vent valve to the fuel tank wall.
It is desirable to provide a method of attaching a polymeric body to a polymeric sheet. It is particularly desirable to provide a low-cost method of integrally molding a body within a blow-molded article. Another object of the invention is to provide a valve and method of attachment which enables a vapor vent valve to be integrally molded within a fuel tank to eliminate the additional assembly steps of affixing or attaching the valve to the tank. If is also desirable to form the fuel tank wall integral with the vapor vent valve.